Managing Predicted Motion Vector Candidates

Abstract

There is provided a method of managing PMV candidates. The method comprises selecting a set of PMV candidates as a subset of the previously coded motion vectors. The method further comprises assigning a code value to each PMV candidate in the set of PMV candidates. The code values vary in length and are assigned to the PMV candidates in order of expected usage such that the PMV candidate having the highest expected usage has one of the shortest code values.

1 . A method of managing Predicted Motion Vector candidates (PMV candidates), the method comprising:
 selecting a set of PMV candidates as a subset of previously coded motion vectors;   assigning a code value to each PMV candidate in the set of PMV candidates, wherein the code values vary in length and are assigned to the PMV candidates in order of expected usage such that the PMV candidate having the highest expected usage has one of the shortest code values.   
     
     
         2 . The method of  claim 1 , wherein the code values assigned to each PMV candidate are assigned according to at least one of:
 arithmetic coding;   Variable Length Coding; and   Context-Based Adaptive Arithmetic Coding.   
     
     
         3 . The method of  claim 1 , the method further comprising removing unnecessary PMV candidates from the set of PMV candidates. 
     
     
         4 . The method of  claim 1 , the method further comprising sorting the PMV candidates in the set of PMV candidates according to expected usage. 
     
     
         5 . The method of  claim 1 , wherein the expected usage of a PMV candidate is obtained from the frequency of use of PMV. 
     
     
         6 . The method of  claim 1 , wherein each PMV candidate corresponds to a motion vector used for coding of a previous block, said previous block having a distance from a current block, and wherein the expected usage of a PMV candidate is obtained from the distances of their respective previous blocks from a current block. 
     
     
         7 . The method of  claim 6 , wherein the distance is measured as a Euclidean distance. 
     
     
         8 . The method of  claim 6 , wherein the distance is measured as a Chebyshev distance. 
     
     
         9 . The method of  claim 8 , wherein the code values are assigned to PMV candidates having common Chebyshev distance according to their Euclidean distance. 
     
     
         10 . The method of  claim 1 , the method for video encoding or for video decoding, wherein the current block is the block being encoded or decoded respectively. 
     
     
         11 . A video encoding apparatus comprising a processor arranged to:
 select a set of PMV candidates as a subset of previously coded motion vectors;   assign a code value to each PMV candidate in the set of PMV candidates, wherein the code values vary in length and are assigned to the PMV candidates in order of expected usage such that the PMV candidate having the highest expected usage has one of the shortest code values.   
     
     
         12 . A video decoding apparatus comprising a processor arranged to:
 select a set of PMV candidates as a subset of previously coded motion vectors;   assign a code value to each PMV candidate in the set of PMV candidates, wherein the code values vary in length and are assigned to the PMV candidates in order of expected usage such that the PMV candidate having the highest expected usage has one of the shortest code values.   
     
     
         13 . A computer-readable medium, carrying instructions, which, when executed by computer logic, causes said computer logic to carry out the method of  claim 1 .